Seat belt tension sensor

Abstract

A seat belt tension sensing assembly fixedly secured to a vehicle. The seat belt tension sensing assembly has a housing and a slide slidably received within the housing, the slide being capable of movement between a first position and a second position within the housing, the second position corresponding to a tension in the seat belt consummate with a child safety seat being secured by the seat belt, the slide having a first opening for a portion of the seat belt to pass therethrough. A sensor is operably attached to the slide and is fixedly secured to the housing. The sensor generates a signal indicative of tension on the slide as the seat belt tension increases corresponding to movement of the slide toward the second position. A compliant member providing an urging force on the slide is operably connected to the slide to urge the slide into the first position. The slide and housing interface at the second position preventing further deflection of the compliant member and further loading on the sensor.

1. A seat belt tension sensing assembly fixedly secured to a vehicle, comprising:
 a housing;  
 a slide slidably received within said housing, said slide being capable of movement between a first position and a second position within said housing, said slide having a first opening for a portion of said seat belt to pass therethrough;  
 a sensor, a first end of which is fixedly secured in said slide, said sensor generating a signal indicative of tension on said slide as said seat belt tension increases corresponding to movement of said slide toward said second position; and  
 a compliant member providing an urging force on a second end of said sensor, said urging force thereby urging said sensor and said slide into said first position;  
 wherein said slide and said housing interface at said second position preventing further deflection of said compliant member and further loading on said sensor.  
 
   
   
     2. The assembly of  claim 1 , wherein said interface between said slide and said housing is a stop feature therebetween, said stop feature is configured to prevent said sensor from exceeding its elastic range when an overload force is exerted between said housing and said slide that exceeds the elastic range of said sensor. 
   
   
     3. The assembly of  claim 1 , wherein said interface between said slide and said housing is a compliant stop feature therebetween, said compliant stop feature having a compliancy between said slide and said housing when an overload force is exerted between said housing and said slide that exceeds the elastic range of said sensor. 
   
   
     4. The assembly of  claim 1 , wherein said slide is configured with at least one of a tab extending therefrom defining a corresponding outboard end of said slide engageable with a corresponding rail extending from said housing to provide a stop at said second position. 
   
   
     5. The assembly of  claim 1 , wherein said sensor is a strain gauge. 
   
   
     6. The assembly of  claim 5 , wherein one end of said strain gauge is fixedly disposed within a second opening of said slide proximate said first opening. 
   
   
     7. The assembly of  claim 6 , wherein said compliant member is disposed at an opposite end of said strain gauge. 
   
   
     8. The assembly of  claim 7 , wherein said compliant member provides one of a tension and compression force on said slide. 
   
   
     9. The assembly of  claim 1 , wherein said compliant member is a spring. 
   
   
     10. The assembly of  claim 9 , wherein said spring is operably connected to said slide and said sensor, said spring provides one of a tension and a compression force relative to movement of said slide from said first position to said second position. 
   
   
     11. The assembly of  claim 1 , wherein said signal is input to a controller configured to suppress a vehicle safety device if said signal meets or exceeds a threshold value. 
   
   
     12. The assembly of  claim 11 , wherein said vehicle safety device is a passenger airbag. 
   
   
     13. The assembly of  claim 12 , wherein said passenger airbag is suppressed when said signal is indicative of a child seat retrained by a corresponding seat belt webbing. 
   
   
     14. The seat belt tension assembly as in  claim 1 , wherein said sensor provides a discrete signal. 
   
   
     15. The seat belt tension assembly as in  claim 1 , wherein said sensor provides a linear signal. 
   
   
     16. A method for limiting damage to a seat belt tension sensor when an overload force is applied, the method comprising:
 receiving a slide within a housing, said slide being capable of movement between a first position and a second position within said housing, said slide having a first opening for a portion of said seat belt to pass therethrough;  
 attaching a first end of a sensor to said slide, a second end of said sensor being fixedly secured to compliant member;  
 generating a signal indicative of tension on said slide as said seat belt tension increases corresponding to movement of said slide toward said second position; and  
 providing said compliant member between said housing and said sensor, said compliant member configured to urge said slide into said first position;  
 wherein said slide and said housing interface at said second position preventing further deflection of said compliant member and further loading on said sensor.  
 
   
   
     17. The method of  claim 16 , wherein said interface between said slide and said housing is a stop feature therebetween, said stop feature is configured to prevent said sensor from exceeding its elastic range when an overload force is exerted between said housing and said slide that exceeds the elastic range of said sensor. 
   
   
     18. The method of  claim 16  wherein said interface between said slide and said housing is a compliant stop feature therebetween, said compliant stop feature having a compliancy between said slide and said housing when an overload force is exerted between said housing and said slide that exceeds the elastic range of said sensor. 
   
   
     19. The method of  claim 16  further comprising:
 configuring said slide with at least one of a tab extending therefrom defining a corresponding outboard end of said slide engageable with a corresponding rail extending from said housing to provide a stop at said second position, said stop configured to limit said sensor to sensing in its elastic range.  
 
   
   
     20. The method of  claim 16 , wherein said sensor is a strain gauge.